Abstract

Background: Osteochondroma or osteocartolaginous exostosis is the most common benign tumor of bone. They account for 35% to 50% of benign bone neoplasms and 10% to 15% of all primary bone tumors. Usually these tumors are found in the appendicular skeleton, especially in the metadiaphyseal region of long bones. Spinal osteochondromas, however, are uncommon especially at cervical level. Clinical presentation: We report the case of a 16 year old boy presenting a hard, gradually progressing, large swelling mass, over the posterior part of the neck causing pain. Radiological images revealed a giant solitary osteochondroma arising from C3 to C6 laminae. The patient underwent complete surgical excision of the tumor. Postoperative outcome was good and recovery from the pain achieved. Conclusion: Solitary osteochondroma of the cervical spine is a rare manifestation of a common bony tumor. Patients affected may present with a multitude of symptoms and complications depending on the size and location of the lesion. Advanced imaging modalities are required for characterization, diagnosis, surgical planning and management of these rare cervical lesions.

Keywords

Osteochondroma, Exostosis, Cervical spine, Bone tumor, Spine surgery

Introduction

Osteochondroma, also known as osteocartilaginous exostosis
or just exostosis, was initially described in 1843 by Reid
[1]; it is a common benign tumor of the bone accounting
for 10% to 15% of all bone tumors and 20% to 50% of all
benign bone tumors [2]. These lesions are the most common
benign tumors of the appendicular skeleton, located in the
metaphyseal region of long bones, particularly the distal
femur and proximal tibia while occur less frequently in the
axial skeleton [3-5]. They occur in a solitary or multiple
form; also called osteochondromatosis or hereditary multiple
exostosis (HME) [6-8]. Spinal involvement accounts for
approximately 3% of cases [5-9]. Any portion of the vertebral
body may be affected. Spinal osteochondromas represent
1.3% to 4.1% of all osteochondromas and for less than 4%
of spinal neoplasms [3,10-15]. The role of the genes or of
the immune system in the pathogenesis of osteochondroma
seems to be less understood as compared to other diseases so
as far for neoangiogenesis [16-20].

The age of onset for spinal osteochondromas is the second
and third decade of life and there is a male predominance (M:
F ratio of 2.5:1) [4,9,14].

Spinal osteochondromas may produce a wide variety of
symptoms and complications depending on their location
and relationship to surrounding structures. These may
include compressive myelopathy, nerve root compression,
pathological fractures and malignant degeneration [8,14].

Case Report

A previously healthy 16 year old boy was referred to our
Department because he noticed a gradually progressing
hard posterior neck mass causing pain and discomfort. Pain
developed when the neck was turned or when local pressure
was applied. No family history of osteochondroma or other abnormalities of the long-bones and appendicular skeleton
was referred.

Physical examination revealed an osseous protuberance,
firmly attached to the cervical spine at the base of the neck
slightly larger on the left. The mass seemed to be continuous
with the cervical vertebrae and terminal ranges of neck’s
movements were restricted. He denied numbness, tingling,
or other neurologic symptoms: no motor deficit, sensory
disturbance, or hyper reflexia was noted.

Computerized tomography scan of the cervical spine was
done: it revealed a well-defined, pedunculated mushroomshaped
mass with a calcified cartilage cap, measuring about
35*26*37 mm, arising from posterior arch of the C3-C6
vertebrae (spinous processes and corresponding laminas) with
corticomedullary continuity and bone remodelling (Figures
1a and 1b). There was no extension within the canal. Preand
post-contrast magnetic resonance imaging confirmed the
presence of the large multilobulated, cystic, and irregularly
enhancing mass with calcified components (Figures 1 c and
1d). The lesion was suspicious for a solitary osteochondroma.

Figure 1a & 1b: Pre-operative neuroimaging (CT scan: 1a, 1b and MRI: 1c, 1d) which reveal a large mass in the posterior region of the neck, strictly adherent to the cervical spine

Surgical treatment was chosen and performed. Under
general anaesthesia and through a posterior-midline cervical
approach the lesion was clearly visualized: it was lobulated,
well-circumscribed with the top surface smooth (Figures 1b, 2a and 2b). The cartilaginous lesion was first resected using
osteotomes and the residue lesion was then thinned down
to the level of the laminae. A wide C3-C6 laminectomy
without facet sacrifice was performed with en bloc resection
of the tumor; there were no adhesions with the dura mater.
Considering the patient’s normal cervical lordosis and
facet preservation, fusion was not thought to be necessary.
The resected piece was sent to the Pathology Department for the histopathological examination. As hemostatic agent
the Vivostat® system (Vivostat A/S, Alleroed, Denmark)
was used, forming an extremely thin white coat without
compression of the neural structures [23-26]. A drain was
applied for 24 h.

Figure 2: (2A) Intraoperative operative view of the Osteochondroma; (2B) Postoperative view which reveals the complete removal of the tumor and the exposed spinal cord

The results of a pathological examination were consistent with
a benign osteochondroma with no evidence of any malignant
transformation. The bony edges of the laminectomy margins
were in healthy tissue.

The postoperative course was uneventful and the patient
recovered soon after surgery; the pain immediately began to
decrease and the neck movements to improve. The patient was
discharged after 3 days. A new examination was performed
one month later; he showed complete clinical recovery
and the postoperative CT scan demonstrated a gross-total
resection with stable sagittal alignment (Figures 3a and 3b).
The patient was completely relieved of his symptoms until
the latest follow up, conducted 1 year postoperatively.

Discussion

Spinal osteochondromas can be of two types: multiple
osteochondromas in patients with hereditary multiple
exostoses, autosomal dominant with full penetrance
syndrome, and solitary osteochondromas occurring in the
spine [4].

The pathophysiology of both remains unclear. Ionizing
radiation could have a role and an association is found in 12
to 15% of cases [27].

Solitary osteochondromas are not considered true neoplasms:
they originate from within the periosteum when a cartilaginous
fragment grows progressively by enchondral bone formation
[8]; this often happen at sites of rapid bone growth in the
immature skeleton [7]. Therefore the lesion is composed of cortical and medullary bone capped by hyaline cartilage with
continuity of the osteochondroma with the native bone cortex
[2,7,8,13].

Cervical osteochondromas represent approximately 50%
of all osteochondromas involving the spine [2,28]. The
atlantoaxial region is the most common location followed
by C7 vertebral body, according to literature; however, any
level of the cervical spine can be affected and, on the basis
of the anatomic region, surgical strategy can be demanding
[2,3,7,10,13,29-31]. The predilection for the cervical spine
is believed to be due to the relatively increased mobility in
this portion compared with the others and its predisposition
of increased stress and microtrauma to the epiphysis and
promoting exostotic growth [13,28]. Osteochondromas arise
most frequently from the posterior elements of the spine
such as the spinous, transverse, and articular processes but
can also arise from the vertebral body, pedicle, and rarely the
facet joints [12,13]. This tendency thought to be related to
the abundance of secondary ossification centers within the
neural arch [28].

As in our case, most solitary cervical spine osteochondromas do
not produce neurological symptoms [10]; rarely do they cause
radiculopathy or myelopathy. Symptoms and complications
depend on location and relationship to associated structures
and are the result of progressive encroachment of the slowly
expanding osteochondroma [9,32]. The most frequent
presentation is myelopathy, more common than radiculopathy
and occurs more than twice as frequently in in the familial
form than the solitary osteochondroma group [10]. Often it
evolves slowly and do not manifest until 20-30 years of age
and for this reason represents a diagnostic challenge [2,33]. A
palpable mass, local pain and cosmetic deformity may occur
with neural arch lesions because these lesions tend to be large
[8]. However, in some cases, the onset of symptoms is acute
after sudden hyperextension of the spine or after a fall. In
the literature some rare clinical presentations are described.
Pharyngeal mass, as a calcified goiter, or with hoarseness or
dysphagia due to compression of the oesophagus, larynx and
trachea by anterior spinal osteochondroma in the neck have
been described [8,14,21]. Cervical osteochondromas may
produce Horner syndrome due to compression of the cervical
sympathetic chain by lesion developing anteriorly into the
lateral spinal nerve groove. Arnold’s (occipital) neuralgia has
been seen in case of C2 involvement and a case of sudden
death has also been reported in odontoid osteochondroma
[34]. But also symptoms as headaches, cranial nerve palsy,
vertigo or obstructive sleep apnea are described [15].
Finally, complications of cervical osteochondromas include,
compressions of vertebral artery, subclavian artery and the
common carotid artery, pathologic fracture and bursal and
pseudoaneurysm formation [8,34,35]. In our case, there was
no neurological deficit. However, there was a neck pain and
movement limitation caused by the effect which arose from
the large mass of the osteochondroma.

Apart from the risks of local compression, malignant
degeneration, usually into a chondrosarcoma, is the most
fearsome complication. It occurs more commonly in axial
osteochondromas and in less than 1% in the solitary forms [6,8,22]. On MRI, a feature suggesting malignancy is when the cartilage cap thickness is >2 cm in adults and >3 cm in children [2,6].

Diagnosis is difficult on plain radiographs because of the
complex image formed by the spine in the area of the lesion;
therefore multiple imaging modalities are often needed to
detect spinal osteochondromas. CT is the imaging modality
of choice to demonstrate cortical and medullary continuity
in spinal osteochondromas and all others typical signs of
spinal osteochondromas [8,12,13,34]. Magnetic resonance
imaging is more useful in defining the intracanal extradural
component of the tumor and the dural compression and to
visualize the hyaline cartilaginous cap [8,12]. These lesions
generally do not show contrast enhancement, although
cases of unusual gadolinium uptake have been described.
Furthermore, bone scintigraphy may be helpful in the
assessment of osteochondromas and can evaluate for the
presence of additional osteochondromas, which are found
in approximately 50% of patients with a cervical spine
osteochondroma [35].

Treatment of symptomatic cervical osteochondromas
consists in surgical excision [13]. The surgical treatment
should be total, including the cartilaginous cap and
underlying intraspinal component. Usually a laminectomy
with decompression of the neural elements has no major
complications and gives good functional results [29].

Incomplete resection, for example in case of intralesional
excision, is associated with a recurrence rate between 2% to
5% of cases [8]. If surgery causes instability due to sacrificing
a significant portion of facets, consideration should be given
to posterior stabilization by instrumentation [12].

Conclusion

Although unusual, cervical osteochondromas should be
considered in the differential diagnosis of spinal tumors.
These lesions have a wide spectrum of clinical presentations
depending on the extent and on the relationship with
surrounding structures. This case report discusses about
a rare location in a pediatric patient of an osteochondroma
arising from the C3-C6 spinous processes and causing neck
pain. Treatment consists in total surgical excision.

References

Reid J. Case of disease of the spinal cord, from an exostosis of the second cervical vertebra. Lond Edinb Mon J Med Sci 1843; 3: 194-198.